We propose to continue and extend our on-going studies of spinal cord reconstruction following massive crush injury of the cord. A microneurosurgical technique, "delayed subpial nerve grafting", has been developed in this laboratory to correct for an autolytic process of the injured spinal cord. The procedure is potentially applicable to human clinical use. In experimental animals, the spinal cords will be compressed to stimulate cord injury seen in human trauma. One week after initial cord injury, the spinal cord will be exposed and necrotic tissue in the gap, the products of cord autolysis, removed subpially without further damaging the spinal cord stumps. Segments of left sciatic nerve will be removed form the same animal and transplanted in the gap, within the intact pia-arachnoid tubing, oriented end-to-end, and closely approximated to the spinal cord stumps. The left sciatic nerve will be reapproximated by end-to-end anastomosis using microneurosurgical techniques. Initial results indicating cord regeneration have been obtained by both light and electron microscopy. Within one month after the grafting, the cord stumps, both above and below the grafts, adhered closely to the grafted nerves. Electron microscopic examination eight months after the grafting showed myelinated spinal cord axons bridging the cord gap via the implanted nerves. At the newly formed junctional node of Ranvier, central type myelin sheath made by oligodendrocytes was seen on one side of the node whereas peripheral type myelin sheath made by the neurilemmal cell was seen on the other. These observations indicate regeneration of spinal axons bridging the gap of injured spinal cord. The animals, three months after grafting, were able to stand and step. Examination showed return of nonvisual placing reflex. To extend the above observations, we propose to conduct: (1) autoradiography, (2) amine fluorescence histochemistry, and (3) evoked potential studies in the grafted animals to determine the origin, destination and functional capability of the regenerated spinal axons.